Well, in camera v. post aside, the pros/cons really only come into play if you expect the users to jump between ratios regularly (especially after framing or in multi-format mode), right? I agree with you in practice with every camera I've ever used (never change ratios and stay full), except the LX7, which I did all the time because of its convenience. On the other side of things, on the near fly cropping has never been easier with WIFI and mobile apps.
I just want every sensor to go 1:1.